The troops were on a mission to show force in an area where the U.S. largely has abandoned small bases.

The heavy firefight lasted hours, with the U.S. soldiers and Afghan forces digging into a muddy hillside.

According to [ABC News' Mike] Boettcher, the Americans and Afghans killed some 50 Taliban fighters and destroyed a Taliban radio headquarters.

When the fighting ended, six American soldiers and one Afghan soldier were dead, with 15 others wounded.

At least seven Medevac helicopters were flown in to rush the casualties to treatment. The operation, called Strong Eagle III, is still ongoing, according to Maj. Gen. John F. Campbell, commanding general of the 101st Airborne Division (Air Assault) in a video teleconference from Afghanistan Thursday.

"There was a significant number of insurgents killed in this operation and several large, large caches found," said Campbell, "We knew this area had a number of insurgents in there. That's why we were targeting this area."